Tuesday, September 02, 2008

Ignorance is a growth industry. One of the fastest moving products is that the temperature of the warmer surface cannot be maintained by back radiation from the colder atmosphere because this violates the second law of thermodynamics. Eli has an argument demonstrating that this is a bucket load of cods wallop, so simple that . . . . (fill in the blank

It goes like this:

The surface is at ~290 K. It radiates ~400 W/m2. In addition there are losses from latent heats (maybe another 100 on average).

The average solar power absorbed by the surface is ~190 W/m2, call it 200 W/m2.

That means, neglecting latent heats, if there is no radiation from the atmosphere absorbed by the earth, the surface will cool until the net outflow of radiation in the IR matches the radiation absorbed from (corrected-ER) the sun.

Do the math E = 200 W/m2 = σ T4, so without back radiation from the atmosphere, the temperature of the surface will reach an equilibrium at 244 K. If you include convection, which is strictly a loss from the surface, the temperature would go even lower.

OTOH, if 200 of the 400 W/m2 radiated into the atmosphere in the IR are returned to the earth from the colder atmosphere, there is a balance between energy absorbed at the surface, Sun + Atm Return =200 +200 and surface radiation = 400 W/m2.

There is still a NET heat flow from the warmer surface to the colder atmosphere (400 - 200 = 200 W/m2) so the second law is obeyed

Slick math, but it still can't work. You still have heat flowing from the colder atmosphere to the warmer earth. Violates 2nd Law at that point. You must look for another reason besides "downradiation" for the fact that the surface is warmer than it "should be." How about Thieme's "windmill?"

No, I like the 'logic' of the denialist fringe, every denizen of said fringe never having a single physics class. Not one denizen. Not one class. So obvious that the stupid burns.

I gave a meteorology lecture several months ago to a high school freshman class, and by the end they understood what the denialist fringe doesn't. Very simple rules of thumb: hi-lo, hot-cold, warm rises, cold sinks. Not hard. Not hard at all.

I wonder if the denialist fringe is embarrassed by the fact that 13-year-olds are more advanced than they are...

Hi jae, don't know what happened, but the point is that YOU don't understand the second law. It might be amusing to calculate the increase in entropy of all the Maxwell's demons needed to bat those photons from the atmosphere away from hitting the surface and being absorbed.

Eli and co. have explained this to you many times. At this point, it's your problem and endlessly repeating the G&T theme song (yes we have no photons today) don't help.

From jae to Eli: Eli, you can't use "net" calculations involving the second law. EVERY STEP has to obey the law. Otherwise, you can prove about anything you want, like my car going uphill without any fuel, as long as someone else burned enough fuel somewhere else to cover it.

jae: "EVERY STEP has to obey the law."In that interpretation of the 2nd law, it's talking about the net change. You can't apply the 2nd law to an individual photon. It doesn't make sense.

The best phrasing of the 2nd law, IMO, is that in a closed system dS/dt ≥ 0; the time derivative of the entropy cannot decrease. While some processes on the Earth (greenhouse effect, evolution, etc.) may appear to decrease entropy, that is only so because the increase in entropy of the sun is not included in the calculation. If you calculate the entropy of the total system (sun+Earth[+universe, if we're really technical about it]), it increases with time, in agreement with the 2nd law.

Make that "quote-mines". By the way, there's nothing wrong with doing arithmetic calculations with your tinfoil hat on, but if the tinfoil hat is interfering with your attempts at arithmetic, then you should really, really go see a doctor.

Atmoz, the entropy of the sun is not increasing - it's decreasing (consider the entropy change in going from hydrogen to helium nuclei.) What does increase is the entropy of the space outside the earth, as the earth radiates.

He does have a point no matter how smart you wanna sound. You have to obey the law or your argument falls apart. Boss Rabbet at Columbia won't like that. He's gunna be a very angry lil bunny if you screw this up.

if jae (jack-ass extraordinaire?) has a point, it is hidden under his tinfoil hat.

and Eli, everyone knows that photons are very smart. After all, they have long known how to go from 0 to "c" in a tiny fraction of a second (atomic emission time) Neither the engineers at GM, the gurus of quantum mechanics nor even Einstein have been able to figure that one out.

I should have been more precise. If you want to think of just an Earth-Sun system, you have to include all those photon and other stuff that the Sun emits that doesn't hit the Earth as part of the Sun. If you think of it as an Earth-Sun-Else system, then you're right; the entropy of the sun would decrease, but would be offset by the entropy increase of the Else.

If photons are not smart, then how do they know enough to produce a pattern of illumination on the other side of a screen based on the number of open slits? (that takes a lot of involved math for us humans)

And how do they know to eliminate the two slit interference pattern when i put a detector next to one of two slits in order to find out which slit the photon went through?

Eli Rabett saidif there is no radiation from the atmosphere absorbed by the earth, the surface will cool until the net outflow of radiation in the IR matches the radiation absorbed from (corrected-ER) the sun.

While it is possible (in principle, at least) to have an atmosphere that absorbs no incident electromagnetic radiation (or no atmosphere at all), it is really not possible to have an atmosphere that would absorb (from sun and earth) and then either not emit at all or emit only in the upward direction (one of which would have to be the case "if there is no radiation from the atmosphere absorbed by the earth")

On a related note:

The atmosphere actually absorbs 67 W/m^2 of the sun's incoming radiation. If the atmosphere did not absorb any energy , more of the incoming solar energy would reach (and be absorbed by) the earth, which would raise the temp from the 244K given above to about 255K (assuming same albedo), the value normally given for an earth without greenhouse effect.

It's sort of a vicious circle. About the only way out I suppose would be an atmosphere with only homonuclear diatomics, in which case you could absorb energy in the UV/VUV but not (effectively) absorb/radiate in the IR. The only way then to dump the energy is chemistry O2 + hv --> O O+O2 --> O3, but wait, O3 is a greenhouse gas......:) You have essentially the same problem with N2, but you need much higher photon energy to do anything (the first strong one photon absorption of N2 is below 100 nm. With anything but an He, H2 atmosphere you have about the same set of problems

"There is still a NET heat flow from the warmer surface to the colder atmosphere (400 - 200 = 200 W/m2) so the second law is obeyed"

Another inconvienient truth from Herr Bunny. This simplistic "netting" does not explain how the decrease in entropy associated with the "backradiation" is balanced (or exceeded) by an increase in entropy elsewhere. Mr. Rabbitt has accounted only for the entropy increase associated with sunlight. This is, indeed, a shell game. What is so BAD, is that the bunny is smart enough to know this.

"Math is not my strong suit. Would you please explain what this post means in English?"

Id say it is far more likely that you are a liar than a chemistry PhD, jae -- and not a very convincing liar at that.

On the outside chance that you do indeed have a PhD in chemistry, you should be required to return it to whatever cracker-jack box that you got it from because based on what you have written here, it is clear that you have no clue whatsoever what the second law of thermodynamics is about.

Thermo is a cornerstone of physical chemistry, or better put, chemical physics. It is well known that organikers are allergic to math and some of the fiercest battles are the organic folk trying to get their students out of pchem classes and comps.

"Thermo is a cornerstone of physical chemistry, or better put, chemical physics. It is well known that organikers are allergic to math and some of the fiercest battles are the organic folk trying to get their students out of pchem classes and comps."

I'm happy to see you say something true. LOL. I HATED pChem. But we chemists DO pick up some of the Pchem stuff. In my case, enough to easily spot a violation of the second law of thermodynamics. I don't believe perpetual motion machines, like the one the AGW crowd is promoting by saying that the colder atmosphere is actually HEATING the earth. Provide some math for this. I just may be able to follow it.

Eli: In my experience (20+ years of teaching undergrad P. Chem. and graduate Stat. Mech. at a Research 1 University) , even the best physical chemistry graduate students do not, in general, have a good conceptual grasp of thermodynamics. That's because they don't really need to - the thermodynamic results that they need were long ago wrapped up in neat little packages (like "delta G^0 = -RT Ln(K)" ) that can be applied without having to agonize over what Gibbs Free Energy means. Most, if not all, physical chemists don't really get Thermo until they have to teach it (Teach, not TA).

You have yet to say anything substantive here. You seem to be just an angry person who is not out to learn anything. I don't know why the bunny allows such obnoxious posting. Whatever, unless you come up with something that contributes to the discussion, I will go back to ignoring you. But do keep the insults coming; I find them funny.

jae: the equations that you ask for can be found (implicitly) in any of the many pulcished monographs on atmospheric radiative transfer. Try Goody and Jung, if you want to see a lot of messy detail. At a more basic level, try chapter 6 of Wallace and Hobbs, _Atmospheric Science: An Introductory Survey_, Academic Press 1977. Pay particular attention to the discussion of Kirchoff's Law on pp. 291-293. Kirchoff's Law is, in essence, the application of the 2nd law of thermodynamics to radiative transfer. Since the fundamental equations of radiative transfer have the 2nd law of thermodynamics built into them, the notion that AGW violates the 2nd law is prima facie absurd.

This from the guy who obviously believes that photons emitted from the colder of two objects somehow "know" (in their infinite photonic wisdom) to avoid the hotter object.

You are one funny guy, jae.

One funny guy.

BTW, you can "debate" what the second law means or does not mean until the cows come home, but it is clear to everyone who reads what you have written that you are denying a simple fact (repeatedly, [over and over {again and again}]):

the global average temp of the earth is ~288K, considerably higher than it would be if the earth did not have an atmosphere that absorbed/emitted in the IR (part of that emitted radiation being directed back toward the earth)

But then as you have already made clear in the previous thread, you either are not familiar with the Stefan-Boltzmann radiation law or you do not know how to take the 4th root of a number (perhaps understandable, math not being your strong suit, being a PhD chemist and all).

So how can we really expect you to actually calculate the temp of the earth sans an IR absorbing/emitting atmosphere (even if you were given the relevant equation, as you were in the previous thread)?

The reference trick again and again and again. I have looked briefly at some of those texts, and they ALL use the same concept of the "backradiation" cartoon nonsense. Do ANY of them consider entropy, which is really what the second law is all about? No, AFIK, they conveniently skip this issue and keep beating on "backradiation." I need to know HOW on this world a cold substance heats a hot substance. EVER. This phenomenon is not known, except in "climate science." Radiation cartoons do NOT explain it, because they ignore entropy (as well as other things). They are a scientific joke, IMHO. If one of them really gets into the issue of how I can warm myself with an ice cube, without violating the second law, point me to THAT one.

MarkeyMouse says: jae is quite correct. It is standard practice for Warmers to get evasive when ask questions they have no answer. The eli method is to say it's all on the web "somewhere", and RobertP employs a version "it's all in standard text books".

I think if people are actually being given an undergrad degree in chemistry (to say nothing of a PhD) without understanding the meaning of the second law of thermodynamics, then that does not say much for the department/university that is granting the degree.

Anyone who actually believes that the second law of thermodynamics somehow prohibits photons emitted by a colder body from being absorbed by a nearby warmer body (ie, that the photons emitted by the colder body will somehow "avoid" being absorbed by the warmer body) has no business being awarded a PhD in any branch of chemistry (organic or otherwise)

That they can go through 9+ years of higher education in science and actually entertain such thoughts is unbelievable (to me at least).

That's as embarrassing (if not more embarrassing) for the department who awards the degree as for the one who got it.

Hey, I've got a chemistry degree, but my maths is rather poor, I'm not much use at calculus. Morevoer, I harbour a deep and abiding grudge for my school and university for not giving me a proper grounding in philosophy of science; instead I have had to learn it all after uni.

But anyway, jae needs to consider which system is under inspection here, which is increasing in entropy? go on Jae, tell us. How does the atmosphere really work in terms of increasing entropy? You see, at the moment, you appear to be in rebellion against every textbook out there on the topic, without actually having ponied up any rational argument as to why they (and by implication the many PhD'd and professored writers) are wrong. Don't tell us its the entropy, show us. And don't forget the Gibbs free energy.

Understanding and being able to apply the basic ideas behind the second law of thermodynamics does not require much in the way of mathematical knowledge.

But it does require having an understanding of the basic underlying assumptions of the law (eg, isolated macroscopic system ) and also the non-applicability of the law to certain (eg, microscopic) cases:

a lower energy molecule can transfer some of its energy to a higher energy molecule, eg through exchange of a photon (emission of the photon from the lower energy molecule and absorption of the same photon by the higher energy molecule). The second law simply does not apply to such a case.

But, in and of itself, the unsubstantiated claim that "AGW violates the second law of thermodynamics" is not even a scientific argument. (Any PhD or even BS chemist should certainly recognize such a statement for what it is: an empty hand-waving argument)

To demonstrate violation of the second law of thermodynamics (or violation of any other physical law) one must show precisely how something violates the law, which, of course, requires that one first know what the law actually says -- and means.

If Marky wants full spectrum emission from the top of the atmosphere, there is always Nimbus 3 and Nimbus 4 from the 1960s and 70s, AIRS, AURA, a bunch of balloons and more. Google is your friend. Ignorance and attitude don't make for a good mixture Marky.

"Rabett: "Guys, I don't think you want to mess with Robert about Pchem or thermo. You really will get undressed."

LOL. Now, we are being threatened by being "insulted" by a big guy? Somehow, I'm not very afraid.

Why the heck can't he (or the funnybunny) at least present some page numbers. At best, he could present some equations showing how the AGW CO2-warming theory does not violate the second law.

At the very best, he could provide what Steve McIntyre has been asking for for over 2 years: a sensible first-principles exposition of how CO2 can heat the atmosphere, and especially how the "positive feedback" idea works. Like Steve, I've been waiting for over two years for such a document. Since it has not been forthcoming, I don't believe it exists, which suggests strongly that the "warmers" are engaging in absolute fraud. The warmers ALWAYS point to all kinds of books and articles, so they can duck this question and avoid answering it. Bring it on, Robert!

To those claiming there are no top-of-atmosphere IR emission spectral measurements. Try Googling...

ir atmospheric emission spectrum toa

To those who claiming that the green house effect violates the 2nd law of thermo...pick up a text book or something. The original post spells it out. If you can't see that, then there is no hope for you

Maybe those chemistry PhD:s sleep without a blanket too. As it is, the colder blanket can not warm the body, it would contradict the second law of thermodynamics! It doesn't matter if it's radiation, conduction or convection, "a cooler body can't warm a warmer one".

Blankets are only a marketing scam by textile companies.

Also their computers have no heat sinks or coolers either, since after the processor gets one degree hotter than the surroundings, the as heat will always flow perfectly in one direction.

Actually, they don't even need a house, since insulation is not a phenomenon but a hoax (by the nefarious insulation industry no less). A shed will do (to keep dry), and some hot radiators, or a fireplace.

"Our Heatsheet® Survival blanket is 20% larger than competing brands-allowing you to shelter two people inside. Survival and first aid instructions are printed directly on the blanket! Reflects up to 80% of radiant body heat."

Hmm, guess returned radiation keeps the little lost Rabetts warm and cozy.

LOL. The bunny must be desperately looking for something to chew on, lately. I don't know WHO besides you mentioned survival blankets, which are a very special type of "blanket." Another Hare-brained tangent. As the bunny probably knows, open air is one of the absolutely worst insulators on the planet, due to convection (which is another reason the CO2/AGW idea is so silly). But air is, alas, a poor conductor, also. So, if you take a material with low mass (to minimize conduction)and use it to surround billions of very tiny air bubbles(to minimize conduction), you get the best type of insulation known, other than a vacuum, where there is no convection. It's called foam insulation.

How does the photon know the temperature of the source from which it was emitted? How does it know the temperature of the body it is hitting? How does the photon know it is hitting the surface or being absorbed by a greenhouse gas or headed out to space? JAE has some really smart photons there.

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Eli Rabett

Eli Rabett is a not quite failed professorial techno-bunny, a chair election from retirement, at a wanna be research university that has a lot to be proud of but has swallowed the Kool-Aid. The students are naive but great and the administrators vary day-to-day between homicidal and delusional. His colleagues are smart, but they have a curious inability to see the holes that they dig for themselves. Prof. Rabett is thankful that they occasionally heed his pointing out the implications of the various enthusiasms that rattle around the department and school. Ms. Rabett is thankful that Prof. Rabett occasionally heeds her pointing out that he is nuts.